1. Field of the Invention
The present invention relates to an image forming apparatus which is configured so as to arrange fine particles of a developer in an image-wise manner at an image-forming section to form an image by the developer onto a recording medium. Further, the present invention relates to a developer cartridge (or a developer supply cartridge) removably provided (or attached) in a body frame of the image forming apparatus, the cartridge being configured so as to accommodate the developer and to be capable of supplying the developer to the image-forming section at which the fine particles of the developer is to be arranged in an image-wise manner in the body frame.
2. Description of the Related Art
An image forming apparatus is widely known, which is configured so as to form an image by use of a developer which is composed of fine particles having charging characteristics. The image forming apparatus is configured, by charging the developer and arranging in an image-wise manner the charged developer with electrostatic action, so as to form the image by the developer onto a certain recording medium.
A development device is accommodated in the image forming apparatus. Within a case serving as a casing of the development device, a developer accommodation chamber is formed. Within the developer accommodation chamber, the developer of nonmagnetic-monocomponent having positive charging characteristics is accommodated.
There is provided a developing chamber which communicates with the developer accommodation chamber within the case. In the developing chamber, a developing roller is rotatably supported. The developing roller is configured so as to be capable of carrying the developer on its circumferential surface. Further, a layer thickness control blade is attached to the case. The layer thickness control blade is composed of a thin plate-like member having an elasticity and is capable of controlling an amount of the developer carried on the developing roller up to a predetermined amount.
In this image forming apparatus, there may arise a problem that the developer leaks from the development device (especially, from both end portions of the developing roller), and thus an image, which is being formed, is disarranged, for instance. In order to avoid the problem, a side sealing member is provided in the development device. The side sealing member is attached at both end portions of the case by use of a two-sided tape.
As a conventional art of this type, a development device and an image forming apparatus disclosed in Japanese Patent Application Laid-Open (kokai) No. 2001-134080 are known. A side sealing member disclosed in the patent application includes a sponge layer and a felt member.
The sponge layer is composed of urethane sponge having a predetermined thickness, sufficient flexibility, and less permanent deformation in compression. The felt member is a member which constitutes a top layer of the side sealing member. The felt member and the sponge layer are pasted together. The felt member is pressed against the developing roller by the sponge layer with a predetermined pressing force.
In the development device and the image forming apparatus having the configuration described above, the developing roller is rotated while the felt member frictionally slides on the circumferential surface at both end portions of the developing roller during the image forming operation. In this case, the sliding portion between the circumferential surface and the felt member restrains the leak of the developer to an outside of the development device.
However, in the conventional development device and image forming apparatus described in the above-mentioned Japanese Patent Application Laid-Open (kokai) No. 2001-134080, there is a possibility that the developer enters (intrudes) into the sliding portion during repetition of the image-forming operation. If the image-forming operation is continuously performed under this condition for a long time, temperature of the sliding portion may increase due to heat caused by the friction, and whereby the developer, which has been entered into the sliding portion, may melt.
The developer which has melted due to the high temperature of the sliding portion caused by the frictional heat may become solidified with caking (sticking) onto the felt member. This may cause deterioration in a close contact condition in the sliding portion between the circumferential surface at the both end portions of the developing roller and the felt member. This deterioration in the close contact condition may cause the developer to leak from the sliding portion. That is, the developer may leak from the both end portions of the developing roller in the development device.